Proleric, some years ago I came across a method to increase the creature viewdistance by modifying some 2da or other in the Omnibus. It may have had to do with ranges.2da, maybe something else. Maybe a combination of something elses. This was quite a while ago. I explored whatever method it was a bit and, IIRC, found that it could cause negative unintended consequences, performance-wise. Pretty vague, I know, but the "tweak", whatever it was, was one of my candidates for unexpected, mysterious lag I encountered on certain servers I had played on.
If you come across something that achieves what you're looking for, give it some thorough testing and make sure that whatever you do doesn't knock something else off kilter.